| RDI | recommended daily intake; respiratory disturbance index; rupture-delivery interval |
|---|---|
| RFI | radiofrequency interference; recurrence-free interval; renal failure index |
| SDI | standard deviation interval; survey diagnostic instrument |
| UAI | uterine activity interval |
| VI | Roman numeral six; vaginal irrigation; variable interval; vastus intermedius; virgo intacta; virulen... |